Chemical composition and biological characterization of extracts of male-produced pheromone fromAmblyomma cajennense(Fabricius, 1787) (Acari: Ixodidae) by GC/MS-SIM and behavioural responses

The extract from fed Amblyomma cajennense (Fabricius) males was characterized for chemical composition and behavioural responses. The pheromone was obtained by extraction in hexane, analysed by gas chromatography/mass spectrometry-single ion monitoring and subjected to behavioural bioassays in vitro and in vivo. The presence of 10 constituents already identified in tick pheromones was evaluated and qualitative analysis of the extract indicated the presence of benzaldehyde, benzoic acid, nonanoic acid, salicylic acid, 2,6-dichlorophenol, limonene and methyl salicylate and the absence of butyric acid, isobutyric acid and o-nitrophenol. In an olfactometer bioassay, males, females and nymphs were not attracted by the extract (P > 0.05) as the displacement angles (0°–10°) distribution was similar between tests (13.3–38.6%) and controls (8.5–23.7%). Similarly, there was no statistically significant aggregation response of test ticks to extracts in bioassays in vitro. However, significantly greater attachment (P...